Quickly preview your site on other Mac or iOS devices via Handoff (OS X Yosemite Only). When publishing is complete, and the publishing window remains open, you can launch Safari on other devices via Handoff to preview the published website.

It’s nothing more than Mac Handoff, which as far as I’m concerned does not need to be noted in the completed Publish window. I know how Handoff works, but seeing the note about it there under the completed progress bar makes me think that in this case in RW there’s something more to it than there really is.

A number of folks, when we previewed the feature to them, were surprised that this is possible - Handoff is not used a great deal for passing plain-old URLs to open in Safari, normally it’s used between copies of an app on different devices. This hint is deliberately there so people get a nudge about the ability to hand off, as it appears when RapidWeaver notifies the Handoff system that the URL should be “broadcast”.